Butterflies of
Thailand, Malaysia &
Borneo
Common Tree Nymph
Idea stolli
MOORE,
1883
Family - NYMPHALIDAE
subfamily -
DANAINAE
Tribe - DANAINI
introduction
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habitats |
lifecycle |
adult behaviour
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Idea stolli,
Singapore
( image © Henry Koh
) |
Introduction
The
subfamily Danainae, which includes the Monarchs, Tigers, Crows and Tree
Nymphs,
comprises of about 190 species worldwide.
All
Danaines are thought to be distasteful to birds. Their bodies contain toxins
which are derived from the lactiferous larval foodplants,
and are often supplemented by further toxins sequestered from adult food sources.
The
bright wing patterns "advertise" these unpalatable qualities, in much the same way that the bands of yellow and black of wasps
advertise the fact that they can sting. Consequently any bird that suffers the
highly unpleasant experience of tasting a Danaine
is unlikely to attack other similarly coloured butterflies. Effectively, a few
individuals are sacrificed for the good of the species as a whole.
There are 12 Idea species, of
which 5 occur in West Malaysia i.e. hypermnestra,
leuconoe, lynceus,
iasonia and stolli.
The other 7 species are found variously in India, Sri Lanka, Myanmar, Thailand, the
Philippines, Sumatra, Borneo, Sulawesi, Irian and Papua New Guinea.
Tree Nymphs are
very large butterflies, characterised by having translucent white wings
patterned with black veins, and numerous oval black spots. They are
noted for their slow and very graceful flight, which gives them the appearance
of white handkerchiefs floating gently on the breeze.
Idea stolli occurs
in West Malaysia, Singapore, Borneo, Sumatra and Java.
Habitats
This is a relatively common species occurring in primary and secondary
rainforest and cloudforest at altitudes between sea level and about 1200m.
Lifecycle
The egg is melon-shaped
and hexagonally pitted, with a flattened base. It is laid singly on leaves of
Agonosma ( Apocynaceae ).
The caterpillar black,
with a series of broad white transverse bands, and has bright pink lateral patches on the 2nd and 7th abdominal segments.
It has a pair of long black filaments extending from each of the thoracic
segments, and a shorter pair on the anal segment. These filaments
probably
disseminate pheromones that may function to ward off predators or parasitoids.
Adult behaviour
I have spent many happy hours watching this beautiful species at
various sites in Sarawak and Sabah. The
butterflies have a very slow and extraordinarily graceful flight. In
the mornings they habitually ascend to the tree tops to feed at
Syzygium
or Eugenia
flowers. In late afternoon they "parachute" very gently down in
groups of up to half a dozen, weaving and circling until they
settle, typically on a large leaf several metres above ground
level.
The slow flight might be thought to
make them easy prey for birds, but like all Danaines
Idea are poisonous or highly
unpalateable to birds and are not often attacked. The slow flight
is their method of advertising the very distinctive pattern, which
birds, through past experience, associate with a very unpleasant
taste.
In sunny conditions males usually rest with the wings erect or
partly open, ready to take flight to intercept potential mates. In
cool or cloudy weather they are more relaxed and can
sometimes be found feeding at flowers at the side of roads in
hilly country. When feeding they tend to slowly flutter or fan
their wings, but when settled on foliage they will bask with wings
fully outspread.
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